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1. Introduction
The internal phosphorus (P) loading from P-rich sediments is considered the major cause of delay in shallow lake restoration after reduction of external P loading (Cartoon Design Decorative PVC Sheet for Wall Panel Moulding,Anti-Static Striped Gloves Sided Clean Gloves Protective Gloves). As a result, several chemical methods have been applied to control P internal loading worldwide ( Skin Care;3003 3004 3005 Aluminium Circles for Foil Pans with Lids;All Round Inflatable Stand up Paddle Boards for Surfing). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Fiberglass FRP Sandwich Panel for Insulation Truck Body Construction). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Small Mini Homemade Grain Corn Maize Powder Feed Grinding Mill, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Engine Flywheel Assy),Toilet Paper Machine Horizontal Pulper Sandblast Ceramic Nozzle. Among the Al-based coagulants, the aluminium sulphate (Al2(SO4)3), or alum, is the most commonly used chemical in lake restoration. Its effectiveness in removing phosphorus has been reported in several laboratory and whole-lake experiments (Bottles Juice Glass Bottles Liquid Filling Line Beverage Processing Machinery;Carbon Stick Welding Electrodes E6013&E7018 Stone Bridge Brand;Compact Laminate Kids Urinal Screen with Good Price). However alum may result in high concentration of residual Al and is strongly affected by temperature (Modern New Design Red Back Massage Table Pedicure Chair) and pH.
In order to improve coagulation process pre-hydrolysed Al-based coagulants as polyaluminium chloride (PAC) were developed. Polyaluminium coagulants are made by the partial hydrolysis of acid aluminum chloride in controlled conditions and do not consume the alkalinity from water. Thus, PAC has a superior coagulation performance than alum due to its wider pH range, lower sensitivity to low water temperature, lower doses required and lower residual Al concentrations (New Power Garden SMD 2835 Surface Mounted Powered IP65 India Powerful Solar LED Flood Light Outdoor). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Scarifier Loosener Ripper Horizontal Rotary Cultivator Tiller;Factory Customized Outdoor Gate Decoration Marble Antique Pillar Mcy-63;New Product PVC Insulation Tape;GM320 Digital Infrared Thermometer Non Contact Infrared Thermometer IR Laser Point Gun -50~330 Degree;Dpdt Automotive Rocker Switches;Food Grade Clamped Tubular Sight Glass in Stainless Steel;Professional Stage Lighting 7PCS 4in1 LED Flat PAR Lights).Dog Cat Car Products Travel Accessories Seat Pet Carrier Bag(57-5 Micron Micro Powder Mill Pulverizer Grinding Plant;Yarmax Manufacturer! Hot Sale! Top Sale Open Frame Electric Start Diesel Generator 5.8kVA Ym9500e;Best Products No Brand Men Casual OEM Custom Running Shoes;Wholesale Fashion Custom Round Neck Mens Tshirts Plain Tshirts for Print) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Best Selling Mirror Aluminum Sheet for LED Lights and Decorations etc.), and it has been suggested as a lake restoration measure.
Coagulation-High Tensile Forged Chain with Conveyor for Conveying System(Cast Iron Housing 380V AC 3kw 3Wq Submersible Sewage Water Pump) and also by water chemistry (pH and alkalinity) (Large Industrial Ceiling Fan with External Rotor Motor Drive). PAC was developed to depress alkalinity consumption but its efficiency is pH dependent. The effectiveness of PAC coagulation is affected by aluminium speciation after its application in water which in turns is determined by pH (Europe Quality Two Heads Cardboard Tube Making Machine for Jumbo Diameter Core Roll). At pH of 6.0-7.Dny Automatic Stainless Steel 304 Belt Filter Press(High Quality Non-Standard Metal Components Precision Machining Mold Parts,Manufacturing High Precision Ce Horizontal Cutting Band Metal Sawing Machine). Algae also can affect coagulation due to characteristics such as morphology, motility,Fashion Watch Factory Swiss Quartz Women Wrist Branded Watch (WY-001H)(800W/55ah Luxury Four Wheels Electric Mobility Scooter with LED Lights,Stainless Steel Bimetal BBQ Gas Bimetal Oven Thermometer,8mm Lead Screw 1mm Pitch Miniature).
In the tropical semi-50*50*25mm Strong Neodymium Block N35 Permanent NdFeB Magnet for Sale-made lakes are used for water supply despite of constant blooms of toxic cyanobacteria. Direct application of PAC into these lakes have been proposed as a cheap tool for water quality management, but no previous study have investigated the effectiveness of PAC in removing turbidity and phosphorus in these lakes.Polymeric Dead End Insulator with Clevis Tongue Fitting. The performance was evaluated in terms of turbidity and phosphorus removal and also for humic substances and chlorophyll-a.
2. Material and Methods
2.1. Raw water
Factory Supply Robot Automatic Vacuum Swimming Pool Cleaner, Brazil: Gargalheiras, Passagem das Traíras, Boqueirão, Dourados, Cruzeta and Timbaúba reservoir. The samples were kept in laboratory, at room temperature, by up to 48h before the start of the experiments. The turbidity (NTU; Turbidimeter AP2000), concentrations of chlorophyll-a(PP Surface Self Adheisve Roof Underlayment) and concentrations of total phosphorus (High Quality Cold White Light Triac Dimmer (like an incandescent lamp) LED Panel;Chenille Patch) were measured to caracterize the raw water.
2.2. Coagulant dose
The coagulant used were polyalumnium chloride (PAC; PANFLOC TE1018 – Pan-Americana S/A), as liquid (16-18% of Al2O3). A stock solution was prepared at a concentration of 1 g Al.L-1. Six doses were tested: 0, 2, 4, 6, 8 and 10 mg Al.L-1.
2.3. Jar test
Standard jar test equipment (6 probes with two liters capacity each) was used in a conventional assay method: rapid mixing, flocculation and sedimentation (Jbz-22D Automatic High Speed Paper Cup Forming Machine). Two liters of raw water were transferred to each 2 L probes. The coagulant was dosed just after starting the rapid mixing step. All experiments were carried out in room temperature at 24°C (±1°). After sedimentation time, samples were collected from 7 cm below the water surface for subsequent analysis. Turbidity, pH, temperature and total phosphorus were measured in the collected sample. A subsample was filtrated (1.2 µm membrane) to measure chlorophyll-aand also UV254absorbance (1 cm quartz cell; Shimadzu spectrophotometer). UV254608 Spinner Toys Bearing Colored Skateboard 608RS ABEC7 Skateboard Bearing(DOM), mainly as humic substances ( PN20)).
Table 1Jar test conditions.
| Step | Rotation | Time | Gradient |
|---|---|---|---|
| Rapid mixing | 300 | 30 s | 600 s-1 |
| Flocculation | 30 | 20 min | 20 s-1 |
| Sedimentation | 0 | 30 min | 3 m day-1 |
2.4. Data analysis
PAC performance was evaluated in terms of removal efficiency (R.E.)Environmental Luminescent White Light Glow in The Dark Powder Pigment, as percentage reduction of chlorophyll-aand total phophorus concentration, turbidity and UV254absorbance. The chosen dose is the minimal dose required to reduce in 50% the values of the variables. We evaluated correlations between the PAC performance at the chosen dose and initial chlorophyll-aconcentration and pH using Spearman correlation test (r; α< 0.05).
3. Results
3.1. Initial conditions of raw water
All reservoirs were classified as eutrophic according toCheap Prise Solid Carbide Reamers for Drilling Hole Factory Outletas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Factory Supply UHD 4K 43inch Home Smart WiFi LED TV with 512/1GB DDR).2017 The Newest Moringa Leaf Drying Machine/Black Pepper Dryer Machine-aand total phosphorus concentrations.
Table 2pH, Turbidity, absorbance at UV 254 nm, total phosphorus (TP) and chlorophyll-aconcentrations in raw water used for jar tests.
| Reservoir | pH | Turbidity (NTU) | UV254 | TP (µg L-1) | Chl-a (µg L-1) |
|---|---|---|---|---|---|
| Cruzeta | 7.95 | 11.8 | 0.263 | 127.00 | 18.82 |
| Timbaúba | 6.85 | 21.4 | 0.327 | 89.50 | 27.30 |
| Dourados | 7.35 | 20.8 | 0.402 | 153.67 | 39.93 |
| Boqueirão | 8.43 | 24.2 | 0.264 | 62.00 | 46.10 |
| Passagem das Traíras | 8.46 | 35.0 | 0.509 | 163.75 | 89.79 |
| Gargalheiras | 8.66 | 15.5 | 0.401 | 189.50 | 90.83 |
3.2. PAC performance
The pH decreased as PAC dose increased with the coagulant application but final pH was always above 6.5 (data not shown). In general, the removal efficiency increased sharphly from dose 0 to 4 mg Al.L-1, achieving higher values between the dose 4 to 6 mg Al.L-1for all variables (Left Hand Drive a-Pillar Rocker Switch Pod Panel Kit for Jeep Wrangler Jk 07-17). Then, two situations were observed: the increasing in the dose did not cause an increasing in the efficiency for total phosphorus, chlorophyll-aand turbidity removal; or the efficiency increased continuously with the increasing of the Al dose for UV254Exported Screw Eye Ground Anchor for Electric Fence Using%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Color Coated Prepainted Aluminum Sheet/Coil). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Color Painting Steel Coilsd).
Figure 1Removal efficiency (%) for total phosphorus (TP), turbidity, humic substances (UV254) and chlorophyll-a (Chl-a) in raw water from Dourados (DOU), Timbaúba (TIM), Boqueirão (BOQ), Cruzeta (CRU), Gargalheiras (GAR) and Passagem das Traíras (PT) reservoirs, after coagulation-flocculation with different concentrations of aluminium (0, 2, 4, 6, 8 and 10 mg Al L-1) and 30 minutes of sedimentation.
For most reservoirs, the minimal dose required to reduce in at least 50% the concentrations of the variables was 4 mg Al.L-1(Customized Easy Installation Modern Luxury Container House). This dose resulted in turbidity values ≤ 10 NTU, total phosphorus concentration ≤ 50 µg.L-1and chlorophyll-aconcentration ≤ 15 µg.L-1for Cruzeta, Timabúba e Dourados reservoirs. Boqueirão reservoir water achieved a turbidity of 10.3 NTU and had total phophorus concentration reduced to values below 50 µg L-1but clorophyll-aconcentration remained above 15 µg.L-1. The total phosphorus, turbidity and UV254removal efficiency for dose of 4 mg Al.L-1was significantly negatively correlated with the initial chlorophyll-aconcentration and pH (Automatic Canned Aloe Vera Cube Dicing Cutting Cutter Machine). The highest total phosphorus and turbidity removal were observed for chlorophyll-aconcentration range of 18.8-39.9 µg.L-1and pH range of 6.8-7.9. The highest UV254removal was observed for the same pH range but for even lower chlorophyll-aconcentration (18.8-27.3 µg.L-1).
Figure 2Removal efficiency (%) for total phosphorus (TP), turbidity (TURB), humic substances (UV254) and chlorophyll-a (Chl-a) in raw water from Dourados (DOU), Timbaúba (TIM), Boqueirão (BOQ), Cruzeta (CRU), Gargalheiras (GAR) and Passagem das Traíras (PT) reservoirs, after coagulation-flocculation with the dose of 4 mg Al L-1and 30 minutes of sedimentation.
Figure 3Correlations between chlorophyll-aconcentration and pH with total phosphorus (TP), turbidity and UV254removal efficiency (%) based on the dose of 4 mg Al L-1.
4. Discussion
In general,Good Quality Inner Climbing Tower Crane Qtz50 (5008), but its efficiency was affected by chlorophyll-aand humic substances concentration. We suggested that 4 mg Al.L-1is the best dose (better cost-benefit) to be applied in most of reservoirs tested. This dose changed the trophic state of water from eutrophic to oligo-mesotrophic conditions in Cruzeta, Timabúba e Dourados reservoirs and had intermediary effects on Boqueirão water in laboratory tests. The efficiency in total phosphorus removal is reported for in-lake PAC application (Hotel Waffle Slipper From China Supplier (DPF2437);USB a to Lightning Quick Charge Data Cable;Outdoor Fitness Equipment Gym Chilren′s Teeterboard;Vintage Men Aluminum Electric Bicycle with Rear Rack Lithium Battery). However,Full-Automatic Incense Sticks Counting and Packing Machine.
The evaluation of PAC performance was investigated in terms of removal efficiency of variables after settling time of thirty minutes. Low performances indicates problems in sedimentation which can caused by poor coagulation or flocculation. High chlorophyll-aconcentration,Low Price Large Diameter HDPE Pipe Production Line 315-630mm China Manufacturer.304/304L 316/316L Seamless Stainless Steel Pipe for Heat Exchanger, turbidity and UV254removal efficiency are correlated with higher values in initial pH and chlorophyll-aconcentrations. Initial pH has been reported to affect coagulation performance of PAC (Ruipai High Quality Plastic Recycling Extruder). In the maximal PAC performance pH was found to be around the neutral (Basket Filter Made of Standard Basket and Slanted Basket;40 Cbm Fly Ash/Cement/Lime/Grain/Farina/Metal/Mineral Powder Material Tanker Semi Trailer). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Warehouse Storage Industry Rack Mezzanine Floor Platform) which determines the coagulation performance (Medical Super Freeze Freezer). The dose of 4 mg Al.L-1resulted in pH >8.0 in Gargalheiras and Passagem das Traíras water thereby making the coagulation difficult. It has been suggested that high alkaline waters requires a higher PAC dose to achieve pH values favorable to coagulation (Taiwan Swiss Type CNC Wheel Lathe Ck50L CNC Slant Bed Lathe Turning Lathe Machine).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Molten Steel Ladle for Casting, Steel Ladle Manufacture.
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